We are developing a high-resolution, low-dose, direct-conversion digital x-ray detector for intraoral dental radiography. The detector will improve intraoral dental imaging with reduced dose, high resolution, and low detector cost. It can be incorporated into existing dental radiography equipment, replacing film-based or scintillator-based systems. The dose efficiency of current scintillator-CCD or scintillator-CMOS photodiode array x-ray detectors is compromised by inefficient conversion of x-rays to light, transport of the light to the detector, and conversion of the light to electric signal. We have successfully developed a new direct x-ray converter material, polycrystalline mercuric iodide (HgI2), which is a high-Z large- bandgap compound semiconductor with outstanding charge collection properties. The proposed detector is a thin film of polycrystalline mercuric iodide for direct conversion of incident x-rays into charge, grown directly onto a CMOS readout. Dose reduction will be achieved due to the very high sensitivity of mercuric iodide films. We expect to sell or license our detector technology to existing intraoral dental imaging equipment vendors. In Phase I of the project, we grew polycrystalline HgI2 directly onto our small- area CMOS readout chip, which we specially designed for compatibility with HgI2. We measured the imaging performance of the prototype device. In this Phase II we will scale the CMOS chip up to dental Size 2, place the CMOS readout into a package suitable for intraoral use, further modify the HgI2 deposition to improve spatial resolution, and complete and test a full product prototype. The product we will develop will help dentists detect hairline cracks and other high-resolution features while patients will benefit from a reduced lifetime x-ray dose. PUBLIC HEALTH RELEVANCE: We will produce an improved x-ray detector for intraoral dental radiography. The detector will reduce the x-ray dose that dental patients receive during their exam while providing dentists with high resolution images at a low cost. The semiconductor-based detector can be incorporated into existing dental radiography equipment, replacing film-based or scintillator-based systems.